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Biomedical subjects

W Grosch

Publications and source records attributed to W Grosch.

At least 19 recordsLinked to original sources
PubMed2002

Character impact odorants of the apple cultivars Elstar and Cox Orange.

Extracts obtained from Elstar and Cox-Orange apples (Malus var. domestica Borkh.) were screened for potent odorants by aroma extract dilution analysis (AEDA). (E)-beta-Damascenone (I), (E)-beta-damascone (II), hexanal (III), (Z)-3-hexenal (IV), (Z)-2-nonenal (V), linalool (VI), butyl acetate (VII), 2-methylbutyl acetate (VIII) and hexyl acetate (IX) were identified in Elstar and I, III-V, ethyl butanoate (X), ethyl 2-methylbutanoate (XI), 1-octen-3-one (XII), (E)-2-octenal (XIII), methional (XIV), (E)-2-nonenal (XV), eugenol (XVI) and wine lactone (XVII) in Cox Orange. The release of odorants by the cultivars was analysed by gas chromatography-olfactometry of headspace samples. Esters X and XI showed the highest odour activities in the air above Elstar apples and ester X, acetaldehyde (XVIII), 2-methylbutanol (XIX) and ethyl methylpropanoate (XX) in that of Cox Orange. Preparation of a homogenate changed the headspace composition of potent odorants. Hexyl acetate (IX) became the key odorant of Elstar and aldehydes III and IV those of Cox Orange. Quantification and calculation of odour activity values indicated I, IV, V, VII, VIII and IX as the character impact odorants of the fruit flesh of the two cultivars. Elstar contained more I, V, VII and IX and Cox Orange more IV than the other cultivar. The concentrations of VIII were similar.

Chromatography, Gas↗
PubMed2001

Apparatus for the quantitative analysis of the aroma of french bread and its loss during storage.

Based on the principles of static and dynamic headspace sampling, an apparatus was developed for the determination of the release of potent odorants from two types of baguette (industrial process or "intensifée" and traditional or "artisanal") differing in their odor profiles. We applied this apparatus to get an insight into the aroma changes of freshly baked French bread, which develops a stale off-flavor within four hours after baking. Model mixtures containing the odorants in the concentrations found by the headspace analysis were evaluated using the apparatus as an olfactometer. By comparing the odor profiles of the models with those of the baguettes, the quantitative data were confirmed. The results indicate that losses of methylpropanal, 2- and 3-methylbutanal and, on the other hand, an increase of hexanal and (E)-2-nonenal led to a stale off-flavor. Furthermore it was suggested that this apparatus is also suitable for precise flavor release studies of other foods.

Bread↗
PubMed2001

Evaluation of the key odorants of foods by dilution experiments, aroma models and omission.

The state of the art in aroma analysis is reviewed with emphasis on aroma-recombination studies using synthetic blends of odorants (aroma models) which have been prepared on the basis of analytical data. The model that matches the original aroma is the starting material for omission experiments which are performed to establish the odorants that actually contribute to the aroma. These experiments are discussed in detail for the aromas of two wine varieties, three olive oils of different provenance, French fries, boiled beef and coffee. The results indicate that odorants with higher odour activity values (OAV, the ratio of the concentration to the odour threshold) are frequently essential for the aroma. However, there are exceptions where odorants with high OAVs are suppressed in the aroma and compounds with lower OAVs are important contributors. These findings are discussed in the light of model experiments which have been reported in the literature to obtain an insight into the perceptual interactions of odorants in mixtures.

Chromatography, Gas↗
PubMed2000

Potent odorants of raw Arabica coffee. Their changes during roasting.

Aroma extract dilution analysis of raw Arabica coffee revealed 3-isobutyl-2-methoxypyrazine (I), 2-methoxy-3,5-dimethylpyrazine (II), ethyl 2-methylbutyrate (III), ethyl 3-methylbutyrate (IV), and 3-isopropyl-2-methoxypyrazine (V) as potent odorants. The highest odor activity value was found for I followed by II, IV, and V. It was concluded that I was responsible for the characteristic, peasy odor note of raw coffee. Twelve odorants occurring in raw coffee and (E)-beta-damascenone were also quantified after roasting. The concentration of I did not change, whereas methional, 3-hydroxy-4, 5-dimethyl-2(5H)-furanone, vanillin, (E)-beta-damascenone, and 4-vinyl- and 4-ethylguaiacol increased strongly during the roasting process.

Chromatography, Gas↗
PubMed2000

Occurrence of 12-methyltridecanal in microorganisms and physiological samples isolated from beef.

12-Methyltridecanal (MT) smelling tallowy, beef-like was formed from plasmalogens when beef was boiled. To clarify the origin of MT, its concentration was determined by a stable isotope dilution assay in bacteria and protozoa isolated from the rumen of bovine animals as well as in the plasma, erythrocytes, and other physiological samples. The highest amounts of MT were found in bacteria followed by protozoa. The MT content of the erythrocytes was small. The results support the hypothesis that microorganisms are the main source of MT of which a small amount is resorbed by the animal and transported to the muscular tissue where MT is incorporated into plasmalogens.

Abomasum↗
PubMed1999

Sensory study on the character impact odorants of roasted arabica coffee.

The potent odorants were quantified in a sample of roasted Arabica coffee. On the basis of the results, 27 odorants were dissolved in an oil/water mixture. The flavor profile of the model obtained was very close to that of the real sample. In duo and triangle tests, the model was compared with models missing one or more odorants. These experiments indicated that 2-furfurylthiol, 4-vinylguaiacol, several alkyl pyrazines, furanones, acetaldehyde, propanal, methylpropanal, and 2- and 3-methylbutanal had the greatest impact on the coffee flavor.

Adult↗
PubMed1999

Study of the effect of DATEM. 1. Influence of fatty acid chain length on rheology and baking.

To answer the question of which fatty acid residue is the most effective, diacetyltartaric esters of monoglycerides (DATEMs) with fatty acids of chain lengths 6:0-20:0 were synthesized. The activity of synthesized DATEMs and commercial DATEM products was studied by means of rheological methods and a microscale baking test with 10 g of flour. Variation of the acyl residue from 6:0 to 22:0 showed that stearic acid (18:0) had the best effect on the baking activity of DATEM (loaf volume increased by 62%). DATEMs containing unsaturated fatty acids (18:1, 18:2) or DATEMs produced from diacylglycerols instead of monoacylglycerols showed a slight increase of the loaf volumes. A slight effect of DATEM on the rheology of dough was observed. However, much greater was the effect on the gluten isolated from doughs prepared with DATEM. The resistance of gluten to extension was increased after the addition of increasing amounts of DATEM (0.1-0.5%). Within the series of DATEMs derived from the homologous series of monoacylglycerols the product based on glycerol monostearate (18:0) showed a maximum increase of the gluten resistance.

Cooking↗
PubMed1999

Development of a stable isotope dilution assay for the quantification of 5-methyl-(E)-2-hepten-4-one: application to hazelnut oils and hazelnuts.

A stable isotope dilution assay was developed for the quantitation of the hazelnut odorant 5-methyl-(E)-2-hepten-4-one by mass chromatography using synthesized [(2)H](2)-5-methyl-(E)-2-hepten-4-one as the internal standard. Application of the method on two batches of commercial hazelnut oils, processed from either roasted or unroasted nuts, revealed 6.4 microg 5-methyl-(E)-2-hepten-4-one per kg of unroasted oil whereas 315.8 microg per kg was determined in the roasted nut oil. The about 50-fold higher amount of 5-methyl-(E)-2-hepten-4-one in roasted hazelnut oil suggested the necessity of a thermal treatment to generate the flavor compound. Pan frying of raw hazelnuts (9 to 15 min) or boiling of the crushed nut material for 1 h in water led to an increase of 5-methyl-(E)-2-hepten-4-one by factors of 600 and 800, respectively, thereby corroborating that the major part of the nut flavorant is formed during heat treatment from a yet unknown precursor in hazelnuts.

Alkenes↗
PubMed1998

Flavour of coffee. A review.

The concept of flavour analysis developed in our laboratory during the last decade to evaluate the key odorants of foods and beverages, is demonstrated in a review on coffee flavour. The results obtained by aroma extract dilution analysis (AEDA), gas chromatography/olfactometry of headspace samples and quantitation of potent odorants using corresponding stable isotopomers as internal standards are discussed. Finally, some sensory experiments performed on the basis of data assessed by instrumental analyses of roasted coffee samples are reported.

Coffee↗
PubMed1995

Dependence of the 12-methyltridecanal concentration in beef on the age of the animal.

The content of 12-methyltridecanal (12-MT), which contributes greatly to the characteristic aroma of stewed beef, was determined by a stable isotope dilution assay in meat samples from nine bovine animals of different ages. The results, which were related to the amount of phospholipids (PL), indicate that 12-MT content increases with the age of beef, e.g., from 36 micrograms.g(-1) PL in a 4-month-old calf to 810 micrograms.g(-1) PL in an 8-year-old cow. The increase of 12-MT content in PL per month varied between 8.4 and 10.9 micrograms.g(-1) PL (mean: 9.3 +/- 0.78 micrograms.g(-1) PL). Possibly 12-MT content is suitable as an indicator for the estimation of the age of a beef sample.

Aging↗
PubMed1994

Quantitative analysis of caffeic and ferulic acids in oatmeal. Comparison of a conventional method with a stable isotope dilution assay.

[13C]Caffeic acid and [13C]ferulic acid were synthesized and then used as internal standards for the determination of these acids (free and esterified) in oatmeal. A comparative study indicated that 84% of the ferulic acid, but only 32% of the caffeic acid, which is more susceptible to oxidation than the former, could be found by a conventional analytical approach.

Avena↗
PubMed1988

Photolysis of unsaturated fatty acid hydroperoxides. 4. Fatty acid products from the aerobic decomposition of methyl 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoate dissolved in cyclohexane.

In the presence of oxygen, UV-irradiation of a solution of methyl 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoate (13-HPOD) in cyclohexane leads to a broad pattern of reaction products of which a trihydroxyene, seven epoxyhydroxides, four hydroxydienes, four epoxyhydroperoxides, six oxodienes and an epoxycyclohexylene were identified as the main components. Two oxodienes having a (Z)-double bond adjacent to the carbonyl group and the epoxycyclohexylene are reported for the first time. In contrast to results published recently for the UV-degradation of the 13-HPOD in methanol, the decomposition of the 13-HPOD in cyclohexane results in the formation of the 9-HPOD by a rearrangement of the hydroperoxy group. Consequently the reaction products are formed as mixtures of positional isomers. The reaction pathways leading to the identified compounds are discussed.

Chemical Fractionation↗
PubMed1985

[Detection of low lipase activities in food].

A spectrofluorimetric procedure using 4-methylumbelliferyl esters as substrates was developed for the determination of lipase activity in foods. It was tested with among others whey and egg powders, almonds, pepper, paprika and cinnamon. In addition, some lipase preparations of microbial origin were analyzed. The detection limit of the method is one to two orders of magnitude lower than that of a test paper which contains indoxyl acetate as the substrate.

Dietary Proteins↗
PubMed1985

[Quantitative analysis of auto-oxidation products of cholesterol in food of animal origin].

After extraction with methylene chloride, isolation of the unsaponifiable lipid fraction and enrichment by two-step column chromatography, the oxycholesterols were gas chromatographically separated in the form of their trimethylsilyl ethers on a thin film capillary and identified by mass spectrometry. The three major products of cholesterol autoxidation were cholest-5-en-3 beta, 7 alpha-diol(I) its 7 beta-epimer(II) and 5,6-epoxy-cholestan-3 beta-ol(III). In addition, traces of cholestan-3 beta, 5 alpha, 6 beta-triol and cholest-5-en-3 beta,25-diol were detected in some samples. Quantitative analysis was performed with cholest-5-en-3 beta,19-diol as internal standard. The highest concentrations of I-III were found in spray dried egg powders (total amount 15-60 micrograms/g). Parmesan cheese, butter oil and sausages contained significantly lower levels of I-III (total amount 0.1-2.6 micrograms/g). The concentrations of I-III increased strongly when butter oil and beef tallow were heated at 170 degrees C in the presence of air for a longer period.

Animals↗
PubMed1984

[Contribution of linoleic acid to the bitter taste of poppy seeds (Papaver somniferum)].

In lipids isolated from poppy seeds which tasted "burning-bitter" the off-taste was associated with the free fatty acids fraction. In this fraction linoleic acid predominates, while oxidized fatty acids were among the minor constituents. The taste threshold of linoleic acid emulsified in water with monolinolein lies in the range of 4.0-6.0 mumol/ml. On the basis of its high concentration and relatively low taste threshold we conclude that free linoleic acid contributes significantly to the "burning-bitter" off-taste in poppy seeds.

Chromatography, Gel↗